Cathodal Transcranial Direct Current Stimulation Over the Right Temporoparietal Junction Suppresses Its Functional Connectivity and Reduces Contralateral Spatial and Temporal Perception.

Guo Dalong,Qin Yufei,Zhou Yubin,Yang Jinghua,Jia Hongbo,Wang Cong,Li Jiyuan

doi:10.3389/fnins.2021.629331

Abstract

The temporoparietal junction plays key roles in vestibular function, motor-sensory ability, and attitude stability. Conventional approaches to studying the temporoparietal junction have drawbacks, and previous studies have focused on self-motion rather than on vestibular spatial perception. Using transcranial direct current stimulation, we explored the temporoparietal junction’s effects on vestibular-guided orientation for self-motion and vestibular spatial perception. Twenty participants underwent position, motion, and time tasks, as well as functional magnetic resonance imaging scans. In the position task, cathodal transcranial direct current stimulation yielded a significantly lower response in the −6, −7, −8, −9, −10, −11, and −12 stimulus conditions for leftward rotations (P < 0.05). In the time task, the temporal bias for real transcranial direct current stimulation significantly differed from that for sham stimulation (P < 0.01). Functional magnetic resonance imaging showed that cathodal transcranial direct current stimulation suppressed functional connectivity between the temporoparietal junction, right insular cortex, and right supplementary motor area. Moreover, the change in connectivity between the right temporoparietal junction seed and the right insular cortex was positively correlated with temporal bias under stimulation. The above mentioned results show that cathodal transcranial direct current stimulation induces immediate and extended vestibular effects, which could suppress the functional connectivity of the temporoparietal junction and in turn reduce contralateral spatial and temporal perception. The consistent variation in temporal and spatial bias suggested that the temporoparietal junction may be the cortical temporal integrator for the internal model. Moreover, transcranial direct current stimulation could modulate the integration process and may thus have potential clinical applications in vestibular disorders caused by temporoparietal junction dysfunction.

Highlights

The temporoparietal junction (TPJ) is a pivotal multimodal region, located at the intersection of the lateral occipital cortex, inferior parietal lobule, and posterior end of the superior temporal sulcus (Mars et al, 2012)
We aimed to explore the role of the TPJ in vestibular-guided orientation, for selfmotion perception and for vestibular spatial perception, using tDCS and functional magnetic resonance imaging (fMRI)
The results indicated that cathodal tDCS suppresses connectivity of the right TPJ, right insular cortex (IC), and right supplementary motor area (SMA)

Summary

Introduction

The temporoparietal junction (TPJ) is a pivotal multimodal region, located at the intersection of the lateral occipital cortex, inferior parietal lobule, and posterior end of the superior temporal sulcus (Mars et al, 2012). The detailed functional characteristics and anatomical boundaries of the TPJ remain contested, this region is considered to be a critical nerve center that receives upstream information from visual, auditory, somatosensory, thalamic, and limbic brain regions; all this information converges on the TPJ, where it is integrated and processed (Decety and Lamm, 2007). Using traditional methods requires a large enough sample of patients affected only by TPJ lesions, which may be unrealistic since brain damage normally diffuses to adjacent regions and hampers the generalizability of conclusions. The human brain has a powerful ability to compensate for functional loss (i.e., via plasticity) after neurocortical injury; conclusions drawn from patients with cerebral injuries may be inaccurate

Objectives

Methods

Results

Discussion

Conclusion